Differential expression of connexins during histogenesis of the chick retina

Gap junction (GJ) channels couple adjacent cells, allowing transfer of second messengers, ions, and molecules up to 1 kDa. These channels are composed by a multigene family of integral membrane proteins called connexins (Cx). In the retina, besides being essential circuit element in the visual processing, GJ channels also play important roles during its development. Herein, we analyzed Cx43, Cx45, Cx50, and Cx56 expression during chick retinal histogenesis. Cx exhibited distinct expression profiles during retinal development, except for Cx56, whose expression was not detected. Cx43 immunolabeling was observed at early development, in the transition of ventricular zone and pigmented epithelium. Later, Cx43 was seen in the outer plexiform and ganglion cell layers, and afterwards also in the inner plexiform layer. We observed remarkable changes in the phosphorylation status of this protein, which indicated modifications in functional properties of this Cx during retinal histogenesis. By contrast, Cx45 showed stable gene expression levels throughout development and ubiquitous immunoreactivity in progenitor cells. From later embryonic development, Cx45 was mainly observed in the inner retina, and it was expressed by glial cells and neurons. In turn, Cx50 was virtually absent in the chick retina at initial embryonic phases. Combination of PCR, immunohistochemistry and Western blot indicated that this Cx was present in differentiated cells, arising in parallel with the formation of the visual circuitry. Characterization of Cx expression in the developing chick retina indicated particular roles for these proteins and revealed similarities and differences when compared to other species. (C) 2008 Wiley Periodicals, Inc.

PL spectroscopy of Fermi electrons in regime of the quantum Hall effect

The influence of the interlayer coupling on formation of the quantized Hall phase at the filling factor v = 2 was studied in the multilayer GaAs/AlGaAs heterostructures The disorder broaden Gaussian photoluminescence line due to the localized electrons was found in the quantized Hall phase of the isolated multi-quantum well structure On the other hand. the quantized Hall phase of the weakly-coupled multilayers emitted an asymmetrical line similar to that one observed in the metallic electron systems. We demonstrated that the observed asymmetry indicates a formation of the Fermi Surface in the quantized Hall phase of the multilayer electron system due to the interlayer peicolation. A sharp decrease of the single-particle scattering time associated with the extended states oil the Fermi surface was observed at the filling factor v = 2. (C) 2009 Elsevier B.V All rights reserved

Tectono-sedimentary evolution of the Neoproterozoic BIF-bearing Jacadigo Group, SW-Brazil

The Jacadigo Group contains one of the largest sedimentary iron and associated manganese deposits of the Neoproterozoic. Despite its great relevance, no detailed sedimentological study concerning the unit has been carried out to date. Here we present detailed sedimentological data and interpretation on depositional systems, system tracts, external controls on basin evolution, basin configuration and regional tectonic setting of the Jacadigo Basin. Six depositional systems were recognized: (I) an alluvial fan system; (II) a siliciclastic lacustrine system; (III) a fan-delta system; (IV) a bedload-dominated river system; (V) an iron formation-dominated lacustrine or marine gulf system; and (VI) a rimmed carbonate platform system. The interpreted depositional systems are related to three tectonic system tracts. The first four depositional systems are mainly made of continental siliciclastics and refer to the rift initiation to early rift climax stage; the lake/gulf system corresponds to the mid to late rift climax stage and the carbonate platform represents the immediate to late post rift stage (Bocaina Formation deposits of the Ediacaran fossil-bearing Corumba Group). The spatial distribution of the depositional systems and associated paleocurrent patterns indicate a WNW-ESE orientation of the master fault zone related to the formation of the Jacadigo Basin. Thus, the iron formations of the Jacadigo Group were deposited in a starved waterbody related to maximum fault displacement and accommodation rates in a restricted continental rift basin. The Fe-Si-Mn source was probably related to hydrothermal plume activity that reached the basin through the fault system during maximum fault displacement phases. Our results also suggest a restricted tectono-sedimentary setting for the type section of the Puga Formation. The Jacadigo Group and the Puga Formation, usually interpreted as glacial deposits, are readdressed here as basin margin gravitational deposits with no necessary relation to glacial processes. (C) 2011 Elsevier B.V. All rights reserved.

Effect of the estufagem process on the chemical constituents of Madeira wines

Madeira wine is a product of well-established reputation, whose aroma and flavour is the result of unique combinations. Particularly, its maturation may include estufagem, wherein wine is usually heated at 45 °C for three months. During this period, several chemical changes may occur, so it is essential to assess its impact on the wine. In this sense, the main objective of the thesis was to evaluate the effect estufagem on the chemical constituents of Madeira wine, specifically on those molecules potentially important in the development of its typical features. Firstly, analytical methodologies capable of determining the target compounds, combining precision and reproducibility to execution effectiveness, were developed. Then various monovarietal Madeira wines were analysed during estufagem under standard and overheating conditions in order to assess its effect. The following compounds were evaluated: furans, amino acids, biogenic amines, polyphenols, organic acids and volatile compounds. In addition, the total polyphenolic composition, the antioxidant potential and the colour of these wines were also evaluated. The results show that most constituents change due to the heating process. Particularly, the heating promotes the development of 5-hydroxymethylfurfural (HMF) in sweet wines submitted to estufagem at higher temperatures. Moreover, estufagem provides the decrease of most amino acids, suggesting their involvement in the formation of the bouquet of these wines. Regarding the total polyphenol content and antioxidant potential of these wines they do not seem to be greatly affected by the heating step, however most monomeric polyphenols decrease during this process. The thermal processing of Madeira wines favours the development of the volatile composition, especially of volatiles usually reported as typical aromas of Madeira wines. Finally, it was demonstrated that the thermal degradation of sugars, especially of fructose, promotes the emergence of volatile compounds identified in baked wines.

Hemangiosarcoma of the nictitant membrane in a Brazilian Fila dog: case report

Relata-se o caso de um cão, macho, da raça Fila Brasileiro, com nove anos de idade, acometido por neoformação tecidual na membrana nictitante do olho direito, com cerca de quatro meses de evolução. Realizou-se exame oftálmico rotineiro, a partir do qual se notaram hiperemia e edema conjuntivais, secreção ocular serossangüinolenta e neoformação saliente na conjuntiva da membrana nictitante. Realizou-se a exérese cirúrgica da neoformação. À histopatologia, encontraram-se células endoteliais pouco diferenciadas e pleomórficas que originavam intensa neoformação vascular, compatíveis com hemangiossarcoma da membrana nictitante.

Enhancement of optical absorption by modulation of the oxygen flow of TiO2 films deposited by reactive sputtering

Oxygen-deficient TiO2 films with enhanced visible and near-infrared optical absorption have been deposited by reactive sputtering using a planar diode radio frequency magnetron configuration. It is observed that the increase in the absorption coefficient is more effective when the O-2 gas supply is periodically interrupted rather than by a decrease of the partial O-2 gas pressure in the deposition plasma. The optical absorption coefficient at 1.5 eV increases from about 1 x 10(2) cm(-1) to more than 4 x 10(3) cm(-1) as a result of the gas flow discontinuity. A red-shift of similar to 0.24 eV in the optical absorption edge is also observed. High resolution transmission electron microscopy with composition analysis shows that the films present a dense columnar morphology, with estimated mean column width of 40nm. Moreover, the interruptions of the O-2 gas flow do not produce detectable variations in the film composition along its growing direction. X-ray diffraction and micro-Raman experiments indicate the presence of the TiO2 anatase, rutile, and brookite phases. The anatase phase is dominant, with a slight increment of the rutile and brookite phases in films deposited under discontinued O-2 gas flow. The increase of optical absorption in the visible and near-infrared regions has been attributed to a high density of defects in the TiO2 films, which is consistent with density functional theory calculations that place oxygen-related vacancy states in the upper third of the optical bandgap. The electronic structure calculation results, along with the adopted deposition method and experimental data, have been used to propose a mechanism to explain the formation of the observed oxygen-related defects in TiO2 thin films. The observed increase in sub-bandgap absorption and the modeling of the corresponding changes in the electronic structure are potentially useful concerning the optimization of efficiency of the photocatalytic activity and the magnetic doping of TiO2 films. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4724334]

Structural analysis of the Pimelodus maculatus (Lacépède, 1803) embryogenesis (Siluriformes: Pimelodidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structural and ultrastructural characteristics of the yolk syncytial layer in Prochilodus lineatus (Valenciennes, 1836) (Teleostei; Prochilodontidae)

The yolk syncytial layer (YSL) has been regarded as one of the main obstacles for a successful cryopreservation of fish embryos. The purpose of this study was to identify and characterize the YSL in Prochilodus lineatus, a fish species found in southeastern Brazil and considered a very important fishery resource. Embryos were obtained through artificial breeding by hormonal induction. After fertilization, the eggs were incubated in vertical incubators with a controlled temperature (28 degrees C). Embryos were collected in several periods of development up to hatching and then fixed with 2% glutaralclehyde and 4% paraformaldehyde in 0.1 M sodium phosphate buffer (pH 7.3). Morphological analyses were carried out under either light, transmission or scanning electron microscopy. The formation of the YSL in P. lineatus embryos starts at the end of the cleavage stage (morula), mainly at the margin of the blastoderm, and develops along the embryo finally covering the entire yolk mass (late gastrula) and producing a distinct intermediate zone between the yolk and the endodermal cells. The YSL was characterized by the presence of microvilli on the contact region with the yolk endoderm. A cytoplasmic mass, full of mitochondria, vacuoles, ribosomes, endomembrane nets and euchromatic nuclei, indicated a high metabolic activity. This layer is shown as an interface between the yolk and the embryo cells that, besides sustaining and separating the yolk, acts as a structure that makes it available for the embryo. The structural analyses identified no possible barriers to cryoprotectant penetration.

Structural analysis of the embryonic development in Brycon cephalus (Gunther, 1869)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ultrasonographic evaluation of the conceptus from days 10 to 60 of pregnancy in jennies

Daily ultrasound examinations were conducted from Days 10 to 60 (ovulation = Day 0) of pregnancy to monitor the conceptus in jennies (n = 12). The embryonic vesicle was first detected on Day 11.5 +/- 0.9 (mean +/- SD; range 10 to 13d) and was mobile until movement ceased (fixation) on Day 15.5 +/- 1.4 (range, 13 to 18d). The vesicle was spherical from Days 10 to 18 (mean growth rate, 3.2 mm/d), non spherical (irregular) with a reduced growth rate (0.5 mm/d) from Days 19 to 29, and then grew at a moderate rate (1.6 mm/d) up to Day 46. on average, detection of the embryo proper (consistently located on the ventral aspect of the yolk sac) and embryonic heartbeat were Days 20.7 +/- 1.2 and 23.5 +/- 1.3, respectively. Formation of the allantoic sac was first detected on Day 24.4 +/- 1.7 and was complete on Day 36.8 +/- 1.6. Descent of the fetus (and formation of the umbilical cord) began on Day 37.9 +/- 1.7 and was complete on Day 44.1 +/- 2.1. Crown-ramp length averaged 3.7, 15.4, 22.7, 37.5 and 59.6 mm on Days 20, 30, 40, 50 and 60, respectively. In general, morphologic features and dates of occurrence were similar to those reported previously in the mare. (C) 1998 by Elsevier B.V.

Anatomy and ontogeny of the pericarp of Pterodon emarginatus Vogel (Fabaceae, Faboideae), with emphasis on secretory ducts

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Developmental anatomy and morphology of the ovule and seed of Heliconia (Heliconiaceae, Zingiberales)

The developmental anatomy and morphology of the ovule and seed in several species of Heliconia were investigated as part of an embryological study of the Heliconiaceae and to provide a better understanding of their relationships with the other families of the Zingiberales. Heliconia species have an ovule primordium with an outer integument of both dermal and subdermal origin. The archesporial cell is divided into a megasporocyte and a single parietal cell, which in turn are divided only anticlinally to form a single parietal layer, disintegrating later during gametogenesis. The embryo sac was fully developed prior to anthesis. In the developing seed, the endosperm was nuclear, with wall formation in the globular stage; a nucellar pad was observed during embryo development, but later became compressed. The ripe fruit contained seeds enveloped by a lignified endocarp that formed the pyrenes, with each pyrene having an operculum at the basal end; the embryo was considered to be differentiated. Most of these characteristics are shared with other Zingiberales, although the derivation of the operculum from the funicle and the formation of the main mechanical layer by the endocarp are unique to the Heliconiaceae.

Ultrastructural analysis of the nucleolar aspects at spermiogenesis in triatomines (Heteroptera, Triatominae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Meiotic nucleolar cycle and chromatoid body formation during the rat (Rattus novergicus) and mouse (Mus musculus) spermiogenesis

The aims of the present study were to follow the nucleolar cycle in spermiogenesis of the laboratory rodents Rattus novergicus and Mus musculus, to verify the relationship between the nucleolar component and chromatoid body (CB) formation and to investigate the function of this cytoplasmic supramolecular structure in spermatogenic haploid cells. Histological sections of adult seminiferous tubules were analyzed cytochemically by light microscopy and ultrastructural procedures by transmission electron microscopy. The results reveal that in early spermatids, the CB was visualized in association with the Golgi cisterns indicating that this structure may participate in the acrosome formation process. In late spermatids, the CB was observed near the axonema, a fact suggesting that this structure may support the formation of the spermatozoon tail. In conclusion, our data showed that there is disintegration of spermatid nucleoli at the beginning of spermatogenesis and a fraction of this nucleolar material migrates to the cytoplasm, where a specific structure is formed, known as the "chromatoid body", which, apparently, participates in some parts of the rodent spermiogenesis process. (c) 2007 Elsevier Ltd. All rights reserved.

Nb-containing hematites Fe2-xNbxO3: The role of Nb5+ on the reactivity in presence of the H2O2 or ultraviolet light

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)